This invention relates to heat exchangers, more particularly to a heat exchanger particularly useful for heating dirty wash water.
During many industrial cleaning processes the washing fluid, often water or some other solvent, is heated to enhance its cleaning effectiveness. Some containers, such as railroad tank cars, have large amounts of solid residue built up in them. This residue is usually loosened by spraying a heated cleaning liquid and is carried away by the wash liquid.
In some cases it is desirable to re-use the wash liquid after removing the solid matter. The solids in the wash liquid are commonly eliminated by allowing the dirty wash liquid to remain undisturbed in a settling tank. However, some of the solid particles, including sand, dirt and gravel, may not all be removed from the cleaning liquid. These solids have a tendency to precipitate out while passing through a conventional heat exchanger. This can cause hot spots in the heat exchanger which, in addition to reducing the efficiency of heat transfer, may eventually cause the heat exchanger to buckle and fail.
Another problem associated with heat exchangers involves the differences in the amount various components expand and contract according to their temperatures. The requirement that the designer accommodate this differential expansion factor often results in a design which is more complicated, and therefore more expensive to build, than would otherwise be the case.